Currently, composite restorative filling materials are used extensively by dentists. These materials are synthetic polymers and are typically used in bonding techniques. The composite material is generally applied as a viscous material which is hardened by polymerization. The polymerization of the viscous composite material is also known as a curing step. Many of the present day composite materials are cured by exposing the material with a high intensity light source that includes wavelengths in the ultraviolet and visible regions of the electromagnetic spectrum. It is presently estimated that about 60 percent of dental restorations use light curing techniques. Forecasts predict that in the future as many as 95 percent of dental restorations will use light curing.
Medical studies indicate that exposing the eye to ultraviolet light and blue light in the visible spectrum cause discomfort, reduced vision, and may accelerate or worsen ocular disorders. Specifically, exposure to ultraviolet light has been linked to cornea, lens, and retinal damage, and is believed to be a major cause of yellow-brown cataracts. Exposure to blue light in the visible spectrum has been linked to retinal damage, ocular degeneration, retinitis pigmentosa, night blindness, haze and glare.
At present, the available choices for protecting the eyes of a dental team from an intense light source involves significant compromises. For instance, conventional safety glasses having their entire lenses treated to provide protective filtering of the ultraviolet and blue light are available. Though effectively protecting the eye, this type of eye protection requires the dental team to view the entire field of treatment through the protective layer. The view is entirely shaded which gives a distorted color to teeth, tissue, emitted blood, etc. The distorted colors lead to a lack of contrast among the various elements in the mouth which makes it difficult for the dental team to observe and evaluate the procedure. While the safety glasses can be removed from the wearer's eye to observe the treated area after the light source is disconnected from the power source, the fact that the dental team normally has its hands full makes removal of the glasses cumbersome.
Another choice of eye protection is a colored, hand-held panel that is usually held by a dental assistant. This shield is positioned between the area being exposed to the intense light and the line of vision of the dental team. This protective measure suffers from the same problem associated with the totally colored lenses of the eyeglasses described above, i.e., a lack of contrast in the viewing field. Furthermore, the assistant holding the shield is unable to perform other manual procedures normally needed. As a result, the shield is often not held in place, which results in no protection to the dental team.
Certain devices that serve as sources for the intense light also include a small protective shield mounted on the end of the light source. This shield is generally rotatable so that the shield can be placed within the line of view of the dental team, while the ultraviolet and blue light is being emitted. In addition to the contrast problems described above, the shield's close proximity to the end of the light source, which is normally placed close to or in the mouth, prevents the entire device from being utilized in tight quarters. Generally, if the shield is reduced in size significantly to improve access, the majority of protection is lost.
Existing types of eye protection provide a certain level of eye protection, as discussed above; however, each suffer from significant drawbacks. These drawbacks have left the dental team with the choice of either viewing the treated area with a undesirable loss of contrast, or not using eye protection at all. Accordingly, for at least 10 years, there has been a need in the dental industry for a type of eye protection that will protect the wearer from the ultraviolet light and blue light generated by the light sources used to cure composite materials. The device must be convenient to use and not suffer from the drawbacks of the existing types of eye protection.